Wiping action switch contacts



Jan. 18, 1966 E. T. FIBER WIPING ACTION SWITCH CONTACTS Filed Jan. 29, 1964 I 2o (83%,. 1 E Hi lult /0 /4a I v Ill l l|| United States Patent O 3,230,334 WIPIN G ACTION SWITCH CONTACTS Earl T. Piber, Milwaukee, Wis., assigner to Cutler-Hammer, Ine., Milwaukee, Wis., a corporation of Delaware Filed Jan. 29, 1964, Ser. No. 341,058 2 Claims. (Cl. Zim- 164) This invention relates to electrical switches, and more particularly to switches used in the control of low voltage A.C. circuits. Such circuits are referred to as dry circuits.

The gaseous arc created by the contacts upon closure is absent in a dry circuit switch. Contact closure with a butt action will often not penetrate the surface lm on these contacts, and as a result, no electrical circuit is made. The closure of contacts with a wiping action is an effective means of overcoming this situation as the contacts wipe, or scrape, the insulating film from the contact surfaces.

Toggle switches of the two position type, known as utility switches, are commonly employed in dry circuit control. These switches have sliding contacts, but have only two on positions or an on and an off position, and therefore limit the manner in which the circuit may be controlled.

It is therefore an object of this invention to provide a toggle switch of the three position type which has a performed spring contact member interposed between a rocker type contactor and the stationary contacts whereby movement of the contactor upon a portion of the spring contact will cause the latter to engage the stationary contact with a wiping action.

This and other objects will become apparent in the following specifications and claims when taken in conjunction with the ldrawings in which:

FIGURE l is a view of a switch embodying the invention with a side portion br-oken away;

FIG. 2 is an exploded isometric view of certain parts of the switch; and

FIGS. 3a and 3b are enlarged fragmentary views of a portion of the switch showing the contact action in various positions of its movement.

As shown in FIG. 1, a one hole mounting toggle switch 2 is mounted to a panel member 4 by a locknut 6 and a knurled cap nut 8 threaded onto a bushing 10 of a switch frame member 12. A base 14, having an inner cavity 14a is secured to frame 12 by inwardly clinched tabs 12a formed integral with the frame member.

Switch 2 may be either of the single pole type or of the multipole type as described in Alvin W. Krieger Patent No. 2,248,362, wherein the inner cavity 14a of base 14 is divided into separate compartments for each desired pole by vertical wall members 14b. The illustration in FIG. l is one compartment of such a multipole switch.

The bottom surface of cavity 14a contains a pair of stationary contact member 16 which have shank portions extending through openings in base 14 to the exterior of the switch where they are riveted over, each securing a terminal member 18 to the base. It is to be understood that the switch illustrated is a three position switch with two individual on positions and a center olf position, and that the omission of either stationary contact or other similar modifications well known in the art to this type of switch, will create numerous variations of circuit control.

A single actuator member 20 extends through the bushing into cavity 14a, and is pivotally mounted at a point within the bushing. Secured to the inner end of actuator is a plunger housing member 22 which contains a plunger 24 and a spring 26 for each compartment of the switch.

ICC

A U-shaped fulcrum member 28 is mounted in a central recess formed in the bottom surface of cavity 14a in each compartment of the base 14. Each fulcrum member 28 is secured in its recess by a rivet 30 which extends through the base to the exteri-or, and there secures a center, or common terminal 32 to the latter. Falcrum 28 and rivet 30 are of good electrical conducting material to conduct current from the terminal 32 to a V-shaped, movable contactor 34 which is placed upon pivot 28.

As seen in FIG. 2, V-shaped contactor 34 has a wide central portion with narrower leg portions extending outwardly of the central portion at a lesser angle. The apex of contactor 34 has an arcuate shape to provide a positive center position for the dome shaped end of plunger 24. The central portion of contactor 34 is placed between the vertical legs of U-shaped fulcrum 28, and these legs each have pairs of projections 28a which cradle the narrower leg portions of the contactor to prevent it from moving out of position.

At this point a workable switch is described which would be improved by adding a pair of contacts to the underside of the outer ends of contactor 34. By moving the outer end of actuator 20 to either the left or to the right, as viewed in FIG. l, the plunger 24 will move along either the right or the left leg, respectively, of contactor 34, forcing it downward into engagement with one of the stationary contacts 16 with a butt contact action.

The addition of a winged contact member 36 to the existing switch provides the switch with a wiping contact action. Contact member 36 is made of a spring material which has good electrical conductivity and has its underside plated or otherwise coated with a material of high electrical conductivity. As seen in FIG. 2, contact 36 has a flat central portion which has an aperture for the rivet 30 to pass through. Extending upwardly and outwardly of each end of the central portion are leg po-rtion 38 which have crest-like Ihumps 40 formed at their upper ends. Extending outwardly of humps 40 are horizontal wing portions 42 which have their ends bent slightly upwardly to form a skid for reasons that will become apparent later.

As seen in FIG. l, contact member 36 is placed in the central recess in the bottom surface of cavity 14a between the base 14 and fulcrum 28, and the whole assembly along with terminal 32 is secured by rivet 30. In place of the aforementioned contacts on the underside of the ends of contactor 34, a pair of dome shaped extrusions 44 are formed, which provide a positive stop for contactor 34 and supply additional contact pressure after the initial contact has been made, as will become apparent in the following description of operation of the left-'hand contacts, since the action for either pair of contacts would be the same.

As the outer end of actuator 20 is moved from its center off position to its right-hand position, the inner end with plunger housing 22 moves to the left, causing plunger 24 to move along the upper surface of the lefthand leg of contactor 34. Spring 26 forces plunger 24 into engagement with contactor 34 at all times.

With reference to FIG. 3a, the various parts shown in full lines are in their initial center off starting position. While the action imparted through the actuator 20 is relatively one smooth snap motion, various increments of travel have been depicted by the dot-dash line showings of FIGS. 3a and 3b to more clearly show the deflection of spring contact member 36 and the wiping contact action it imparts.

The rst increment of travel is represented by the dot- `dash line objects whose reference characters have the subscript w in FIG. 3a. The contactor 34W is pivoted downwardly so that its underside engages the crest of hump 40W, forcing the wing portion 42W of spring contact 36 downwardly.

The second increment of travel, also shown in FIG. 3a, has reference characters with the subscript x, The underside of contactor 34x forces the hump 40x, and hence the wing portion 42x of spring contact 36 downwardly until the wing 42x touches stationary contact 16 at the skid formed by its upwardly bent end. This upward bend prevents the end of contact 36 from digging into the upper surface of stationary contact 16. It will be seen that the only deflection of the spring contact 36 thus far is in the area between the base 14 and the hump 40.

The third increment of travel is depicted in FIG. 3b and its reference characters have the subscript ""y. As the contactor 34y is pivoted further downwardly, the wing portion 42) bends in the area where it joins with the hump 40) until the wing 42y becomes parallel to the surface of stationary Contact 16. At the same time the skid portion slides along the upper surface of stationary contact 16 to the left. It can be noticed that the pressure being exerted upon the crest of hump 40y by contactor 34y is causing the hump to flatten out.

The fourth increment of travel, also depicted in FIG. 3b with reference characters having a subscript z, shows the final position of the contacts. The contactor 34z has attened the hump 40z a greater amount which caused the wing 42z to slide further to its left, and the dome shaped extrusion Mz on the underside of contactor 34z has engaged the upper surface of wing 42z with a butt action. Extrusion 44z, together with the pivot point on fulcrum 28, provides a definite height at which contactor .34z ceases its travel to prevent spring contact 36 from becoming distorted beyond its stress point. Extrusion 44z also provides additional contact pressure between the wing 42z and the stationary contact 16. The current How is through terminal 32, rivet 30, fulcrum 28, spring contact 36, and stationary contact 16, tol the terminal 13. Some current may also ow through the contactor 34.

Under movement of the actuator back to its center .ol position, the same wiping action occurs upon the break of contacts 16 and 36 in reverse order of the aforementioned steps.

It is evident from the foregoing description that this method of obtaining a positive wiping action in switches having a rocker type contactor is susceptible to many modifications without departing from the scope of the following claims.

I claim:

1. An electric switch having a base with a central cavity open to one side thereof, a member secured to said base and overlying said cavity to enclose the latter, a fulcrum member mounted within said cavity, a pair of stationary contacts mounted within said cavity and having their contact surfaces on a plane lower than that of the pivot points of the fulcrum member, a pivotally movable contactor mounted upon said fulcrum, an oscillatable actuator biased into engagement with said contactor to pivot the latter alternately toward and away from said stationary contacts, a spring contact member mounted within said cavity between said stationary contacts, said spring contacts having a flat central portion for rigidly securing the latter to said base, a pair of symmetrical legs extending angularly toward said contactor from opposite Sides of said central portion, a wing extending outwardly from each of said legs, each wind overlying a corresponding one of said stationary contacts in spaced apart relation, a crest shaped hump formed between said legs and their corresponding wings, wherein the movement imparted to said contactor from said actuator causes said contactor to act upon said hump tot atten the latter and force the respective wing into engagement with the corresponding stationary contact with a wiping action.

2. The combination according to claim 1 wherein said contactor has a pair of extrusions formed at the ends thereof and said extrusions abut the respective wings upon engagement of the latter with their corresponding stationary contacts to provide a deinite stop for said contactor.

References Cited by the Examiner UNITED STATES PATENTS 1,879,349 9/1932 Lederer 200-166 1,925,612 9/1933 Snell 200-164 X 3,117,197 1/1964 Carling et al. ZOO-67 KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCHAEFER, BERNARD A. GILHEANY,

Examiners. 

1. AN ELECTRIC SWITCH HAVING A BASE WITH A CENTRAL CAVITY OPEN TO ONE SIDE THEREOF, A MEMBER SECURED TO SAID BASE AND OVERLYING SAID CAVITY TO ENCLOSE THE LATTER, A FULCRUM MEMBER MOUNTED WITHIN SAID CAVITY, A PAIR OF STATIONARY CONTACTS MOUNTED WITHIN SAID CAVITY AND HAVING THEIR CONTACT SURFACES ON A PLANE LOWER THAN THAT OF THE PIVOT POINTS OF THE FULCRUM MEMBER, A PIVOTALLY MOVABLE CONTACTOR MOUNTED UPON SAID FULCRUM, AN OSCILLATABLE ACTUATOR BIASED INTO ENGAGEMENT WITH SAID CONTACTOR TO PIVOT THE LATTER ALTERNATELY TOWARD AND AWAY FROM SAID STATIONARY CONTACTS, A SPRING CONTACT MEMBER MOUNTED WITHIN SAID CAVITY BETWEEN SAID STATIONARY CONTACTS, SAID SPRING CONTACTS HAVING A FLAT CENTRAL PORTION FOR RIGIDLY SECURING THE LATTER TO SAID BASE, A PAIR OF SYMMETRICAL LEGS EXTENDING ANGULARLY TOWARD SAID CONTACTOR FROM OPPOSITE SIDES OF SAID CENTRAL PORTION, A WING EXTENDING OUTWARDLY FROM EACH OF SAID LEGS, EACH WIND OVERLYING A CORRESPONDING ONE OF SAID STATIONARY CONTACTS IN SPACED APART RELATION, A CREST SHAPED HUMP FORMED BETWEEN SAID LEGS AND THEIR CORRESPONDING WINGS, WHEREIN THE MOVEMENT IMPARTED TO SAID CONTACTOR FROM SAID ACTUATOR CAUSES SAID CONTACTOR TO ACT UPON SAID HUMP TO FLATTEN THE LATTER AND FORCE THE RESPECTIVE WING INTO ENGAGEMENT WITH THE CORRESPONDING STATIONARY CONTACT WITH A WIPING ACTION. 